GEN28

GEN28 —
Reads a text file which contains a time-tagged trajectory.

Description

This function generator reads a text file which contains sets of three values representing the xy coordinates and a time-tag for when the signal should be placed at that location, allowing the user to define a time-tagged trajectory. The file format is in the form:

time1 X1 Y1
time2 X2 Y2
time3 X3 Y3

The configuration of the xy coordinates in space places the signal in the following way:

a1 is -1, 1

a2 is 1, 1

a3 is -1, -1

a4 is 1, -1

This assumes a loudspeaker set up as a1 is left front, a2 is right front, a3 is left back, a4 is right back. Values greater than 1 will result in sounds being attenuated as if in the distance. GEN28 creates values to 10 milliseconds of resolution.

Syntax

f # time size 28 ifilcod

Initialization

size -- number of points in the table. Must be 0. GEN28 takes 0 as the size and automatically allocates memory.

ifilcod -- character-string denoting the source file name. A character-string (in double quotes, spaces permitted) gives the filename itself, optionally a full pathname. If not a full path, the named file is sought in the current directory.

Examples

f1 0 0 28 "move"

The file "move" should look like:

0 -1 1
1 1 1
2 4 4
2.1 -4 -4
3 10 -10
5 -40 0

Since GEN28 creates values to 10 milliseconds of resolution, there will be 500 values created by interpolating X1 to X2 to X3 and so on, and Y1 to Y2 to Y3 and so on, over the appropriate number of values that are stored in the function table. The sound will begin in the left front, over 1 second it will move to the right front, over another second it move further into the distance but still in the right front, then in just 1/10th of a second it moves to the left rear, a bit distant. Finally over the last .9 seconds the sound will move to the right rear, moderately distant, and it comes to rest between the two left channels (due west!), quite distant.